Zebrafish is a premiere organism to study vertebrate development, physiology, behavior, genetics and disease. Powerful techniques allow efficient generation and recovery of zebrafish mutations affecting genes that regulate developmental patterning, organogenesis, physiology and behavior. Recent advances make it easy to study gene function in transgenic zebrafish and with antisense oligonucleotides. The functions of many, if not most, of these genes are conserved among vertebrate groups. Thus, analysis of zebrafish mutations provides insights into gene function in other vertebrates, including humans. The Zebrafish International Resource Center has been established as a repository that provides animals, materials and services to the research community. This proposal seeks continued funding 1) to provide a centralized repository for zebrafish genetic stocks and research materials; 2) to provide consultation and pathology services; and 3) to develop improved zebrafish husbandry methods. These materials, services and information will be made widely available to the research community.